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.Dd January 26, 2010
.Dt GSS_ACQUIRE_CRED 3 PRM
.Os
.Sh NAME
.Nm gss_acquire_cred
.Nd Obtain a GSS-API credential handle for pre-existing credentials
.\" This next command is for sections 2 and 3 only.
.\" .Sh LIBRARY
.Sh SYNOPSIS
.In "gssapi/gssapi.h"
.Ft OM_uint32
.Fo gss_acquire_cred
.Fa "OM_uint32 *minor_status"
.Fa "const gss_name_t desired_name"
.Fa "OM_uint32 time_req"
.Fa "const gss_OID_set desired_mechs"
.Fa "gss_cred_usage_t cred_usage"
.Fa "gss_cred_id_t *output_cred_handle"
.Fa "gss_OID_set *actual_mechs"
.Fa "OM_uint32 *time_rec"
.Fc
.Sh DESCRIPTION
Allows an application to acquire a handle for a pre-existing
credential by name.
GSS-API implementations must impose a local
access-control policy on callers of this routine to prevent
unauthorized callers from acquiring credentials to which they are not
entitled.
This routine is not intended to provide a "login to the
network" function, as such a function would involve the creation of
new credentials rather than merely acquiring a handle to existing
credentials.
Such functions, if required, should be defined in
implementation-specific extensions to the API.
.Pp
If desired_name is
.Dv GSS_C_NO_NAME ,
the call is interpreted as a
request for a credential handle that will invoke default behavior
when passed to
.Fn gss_init_sec_context
(if cred_usage is
.Dv GSS_C_INITIATE
or
.Dv GSS_C_BOTH )
or
.Fn gss_accept_sec_context
(if cred_usage is
.Dv GSS_C_ACCEPT
or
.Dv GSS_C_BOTH ).
.Pp
Mechanisms should honor the
.Fa desired_mechs
parameter,
and return a credential that is suitable to use only with the
requested mechanisms.
An exception to this is the case where one underlying credential
element can be shared by multiple mechanisms;
in this case it is permissible for an implementation to indicate all
mechanisms with which the credential element may be used.
If
.Fa desired_mechs
is an empty set, behavior is undefined.
.Pp
This routine is expected to be used primarily by context acceptors,
since implementations are likely to provide mechanism-specific ways
of obtaining GSS-API initiator credentials from the system login
process.
Some implementations may therefore not support the acquisition of
.Dv GSS_C_INITIATE
or
.Dv GSS_C_BOTH
credentials via
.Fn gss_acquire_cred
for any name other than
.Dv GSS_C_NO_NAME ,
or a name produced by applying either
.Fn gss_inquire_cred
to a valid credential, or
.Fn gss_inquire_context
to an active context.
.Pp
If credential acquisition is time-consuming for a mechanism,
the mechanism may choose to delay the actual acquisition until the
credential is required
(e.g. by
.Fn gss_init_sec_context
or
.Fn gss_accept_sec_context ).
Such mechanism-specific implementation
decisions should be invisible to the calling application;
thus a call of
.Fn gss_inquire_cred
immediately following the call of
.Fn gss_acquire_cred
must return valid credential data,
and may therefore incur the overhead of a deferred credential acquisition.
.Sh PARAMETERS
.Bl -tag -width ".It output_cred_handle"
.It desired_name
Name of principal whose credential should be acquired.
.It time_req
Number of seconds that credentials should remain valid.
Specify
.Dv GSS_C_INDEFINITE
to request that the credentials have the maximum
permitted lifetime.
.It desired_mechs
Set of underlying security mechanisms that may be used.
.Dv GSS_C_NO_OID_SET
may be used to obtain an implementation-specific default.
.It cred_usage
.Bl -tag -width "GSS_C_INITIATE"
.It GSS_C_BOTH
Credentials may be used either to initiate or accept security
contexts.
.It GSS_C_INITIATE
Credentials will only be used to initiate security contexts.
.It GSS_C_ACCEPT
Credentials will only be used to accept security contexts.
.El
.It output_cred_handle
The returned credential handle.
Resources
associated with this credential handle must be released by
the application after use with a call to
.Fn gss_release_cred .
.It actual_mechs
The set of mechanisms for which the credential is valid.
Storage associated with the returned OID-set must be released by the
application after use with a call to
.Fn gss_release_oid_set .
Specify
.Dv NULL if not required.
.It time_rec
Actual number of seconds for which the returned credentials will
remain valid.
If the implementation does not support expiration of credentials,
the value
.Dv GSS_C_INDEFINITE
will be returned.
Specify NULL if not required.
.It minor_status
Mechanism specific status code.
.El
.Sh RETURN VALUES
.Bl -tag -width ".It GSS_S_CREDENTIALS_EXPIRED"
.It GSS_S_COMPLETE
Successful completion.
.It GSS_S_BAD_MECH
Unavailable mechanism requested.
.It GSS_S_BAD_NAMETYPE
Type contained within desired_name parameter is not supported.
.It GSS_S_BAD_NAME
Value supplied for desired_name parameter is ill formed.
.It GSS_S_CREDENTIALS_EXPIRED
The credentials could not be acquired because they have expired.
.It GSS_S_NO_CRED
No credentials were found for the specified name.
.El
.Sh SEE ALSO
.Xr gss_accept_sec_context 3 ,
.Xr gss_init_sec_context 3 ,
.Xr gss_inquire_context 3 ,
.Xr gss_inquire_cred 3 ,
.Xr gss_release_cred 3 ,
.Xr gss_release_oid_set 3
.Sh STANDARDS
.Bl -tag -width ".It RFC 2743"
.It RFC 2743
Generic Security Service Application Program Interface Version 2, Update 1
.It RFC 2744
Generic Security Service API Version 2 : C-bindings
.El
.Sh HISTORY
The
.Nm
function first appeared in
.Fx 7.0 .
.Sh AUTHORS
John Wray, Iris Associates
.Sh COPYRIGHT
Copyright (C) The Internet Society (2000).  All Rights Reserved.
.Pp
This document and translations of it may be copied and furnished to
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.Pp
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.Pp
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